A cyanine dye, 2-[7-（1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene）-1,3,5-heptatrienyl]-1,3,3-trimethyl-3H-indolium iodide （NK-125）, is doped in 4-cyano-4＇-pentylbiphenyl （5 CB）, and the mixture is sandwiched ...A cyanine dye, 2-[7-（1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene）-1,3,5-heptatrienyl]-1,3,3-trimethyl-3H-indolium iodide （NK-125）, is doped in 4-cyano-4＇-pentylbiphenyl （5 CB）, and the mixture is sandwiched between two pieces of rubbed glass plates. The third-order nonlinear optical properties of the oriented NK-125-SCB layers are measured by the resonant femtosecond degenerate four-wave mixing （DFWM） technique at 760 nm. The third-order nonlinear optical susceptibility of one of the present samples is 5.5×10^-8 esu. The slow DFWM response of the NK-125-SCB layers due to a population grating is accelerated by the increasing laser power because of amplified spontaneous emission （ASE）. On the other hand, we do not observe a similar phenomenon for NK-125- polyethylene glycol （PEG-400）. Oriented NK-125 molecules in nematic liquid crystals must have very high ASE efficiency. Hence the population grating in a DFWM signal disappears within about 4 ps. It is expected that NK-125-SCB can be used as a material for very fast all-optical switching.展开更多
An analog implementation of a novel fixed-frequency quasi-sliding-mode controller for single-inductor dual-output（SIDO） buck converter in pseudo-continuous conduction mode（PCCM） with a self-adaptive freewheeling c...An analog implementation of a novel fixed-frequency quasi-sliding-mode controller for single-inductor dual-output（SIDO） buck converter in pseudo-continuous conduction mode（PCCM） with a self-adaptive freewheeling current level（SFCL） is presented.Both small and large signal variations around the operation point are considered to achieve better transient response so as to reduce the cross-regulation of this SIDO buck converter.Moreover,an internal integral loop is added to suppress the steady-state regulation error introduced by conventional PWM-based sliding mode controllers.Instead of keeping it as a constant value,the free-wheeling current level varies according to the load condition to maintain high power efficiency and less cross-regulation at the same time.To verify the feasibility of the proposed controller,an SIDO buck converter with two regulated output voltages,1.8 V and 3.3 V,is designed and fabricated in HEJIAN 0.35 m CMOS process.Simulation and experiment results show that the transient time of this SIDO buck converter drops to 10 s while the cross-regulation is reduced to 0.057 mV/mA,when its first load changes from 50 to 100 mA.展开更多
Tyrosinase(TYR) is an important polyphenolic oxidase enzyme and usually regards as a biomarker of melano ma cancer.Highly effective tracking TYR activity in vivo will help to study the mechanism of TYR in living organ...Tyrosinase(TYR) is an important polyphenolic oxidase enzyme and usually regards as a biomarker of melano ma cancer.Highly effective tracking TYR activity in vivo will help to study the mechanism of TYR in living organisms and forecasts related diseases.In this study,we present a novel TYR-activatable fluo rescent probe(CHMC-DOPA) for tracking TYR activity in vitro and in vivo.CHMC-DOPA is constructed by incorporating dopamine(DOPA) moiety into a fluorescent chloro-hydroxyl-merocyanine(CHMC)scaffold.Upon exposure to TYR,the dopamine unit in CHMC-DOPA is oxidized to a dopaquinone derivative,and an intramolecular photo-induced electron transfer(PET) process between CHMC fluorophore and o-dopaquinone will take place,the fluorescence of CHMC-DOPA is quenched rapidly.Therefore,the evaluation of TYR activity is established in terms of the relationship between fluorescence quenching efficiency and TYR activity.In our experiments,CHMC-DOPA shows various advantages,such as fast response(8 min),low concentration of TYR activation(0.5 U/mL),good water-solubility,as well as the lowest detection limit(0.003 U/mL) compared with previously reported works.Furthermore,CHMCDO PA also exhibits excellent cell membrane permeability and low cytotoxicity,which is successfully used to monitor endogenous TYR activity in living cancer cells and zebrafish models.CHMC-DOPA performs well,and we anticipate that this newly designed novel platform will provide an alternative for high effective monitoring TYR activity in biosystems.展开更多
This paper investigates processing of fast-response data and corrections of turbulent fluxes obtained by using eddy covariance method based on data collected at an offshore observation tower during three Cold-intrusio...This paper investigates processing of fast-response data and corrections of turbulent fluxes obtained by using eddy covariance method based on data collected at an offshore observation tower during three Cold-intrusion(CI)events in the South China Sea in 2010. This study presents the data processing procedure in detail and compares frictional velocities(u*), sensible heat fluxes(H) and latent heat fluxes(LE) yielded by using different averaging periods and different coordinate rotation methods; evaluates the sonic temperature correction for sensible heat flux and the Webb correction for latent heat flux as a function of 10 m wind speed(u10) during the CIs. The results show(1) that the different averaging periods of 30 min and 10 min cause biases of u*(H, LE) within 5%(15%, 62%). The values of u*(H,LE) averaged from 30 mins are mostly larger than those averaged from 10 mins. We suggest that the averaging period of 10 min is not sufficiently long to capture all scale eddies and recommend 30 min averaging period in calculating turbulent fluxes using eddy covariance method during CIs;(2) that the values of u*(H, LE) obtained from double rotation(DR2) and those obtained from planar fit rotation(PF) have good agreements and correlation coefficients between them are larger than 0.99. Because PF method requires unchanged environment and it is easier to apply DR2 method, we suggest DR2 coordinate rotation method in processing fast-response data; and(3) that the median values of frictional velocity(sensible heat flux and latent heat flux) binned according to 2 m s^(-1) intervals of u_(10) increase(decrease,increase) by less than 9%(4%, 10%) by Coriolis corrections(sonic temperature corrections, Webb corrections), which decreases(decreases, increases) with increasing u10 when u10 are 5-17 m s^(-1).展开更多
文摘A cyanine dye, 2-[7-（1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene）-1,3,5-heptatrienyl]-1,3,3-trimethyl-3H-indolium iodide （NK-125）, is doped in 4-cyano-4＇-pentylbiphenyl （5 CB）, and the mixture is sandwiched between two pieces of rubbed glass plates. The third-order nonlinear optical properties of the oriented NK-125-SCB layers are measured by the resonant femtosecond degenerate four-wave mixing （DFWM） technique at 760 nm. The third-order nonlinear optical susceptibility of one of the present samples is 5.5×10^-8 esu. The slow DFWM response of the NK-125-SCB layers due to a population grating is accelerated by the increasing laser power because of amplified spontaneous emission （ASE）. On the other hand, we do not observe a similar phenomenon for NK-125- polyethylene glycol （PEG-400）. Oriented NK-125 molecules in nematic liquid crystals must have very high ASE efficiency. Hence the population grating in a DFWM signal disappears within about 4 ps. It is expected that NK-125-SCB can be used as a material for very fast all-optical switching.
基金Project supported by the National Natural Science Foundation of China (No.60906012)the Analog Devices,Inc.(ADI)
文摘An analog implementation of a novel fixed-frequency quasi-sliding-mode controller for single-inductor dual-output（SIDO） buck converter in pseudo-continuous conduction mode（PCCM） with a self-adaptive freewheeling current level（SFCL） is presented.Both small and large signal variations around the operation point are considered to achieve better transient response so as to reduce the cross-regulation of this SIDO buck converter.Moreover,an internal integral loop is added to suppress the steady-state regulation error introduced by conventional PWM-based sliding mode controllers.Instead of keeping it as a constant value,the free-wheeling current level varies according to the load condition to maintain high power efficiency and less cross-regulation at the same time.To verify the feasibility of the proposed controller,an SIDO buck converter with two regulated output voltages,1.8 V and 3.3 V,is designed and fabricated in HEJIAN 0.35 m CMOS process.Simulation and experiment results show that the transient time of this SIDO buck converter drops to 10 s while the cross-regulation is reduced to 0.057 mV/mA,when its first load changes from 50 to 100 mA.
基金We gratefully acknowledge the financial support by the National Natural Science Foundation of China(Nos.21702053,21901066,21676075,51603064)Natural Science Foundation of Hubei Province(No.2020CFB601)+1 种基金Outstanding Young and Middle-aged Scientific Innovation Team of Colleges and Universities of Hubei Province(No.T201908)partially supported by Open Funding Project of the State Key Laboratory of Biocatalysis and Enzyme Engineering.
文摘Tyrosinase(TYR) is an important polyphenolic oxidase enzyme and usually regards as a biomarker of melano ma cancer.Highly effective tracking TYR activity in vivo will help to study the mechanism of TYR in living organisms and forecasts related diseases.In this study,we present a novel TYR-activatable fluo rescent probe(CHMC-DOPA) for tracking TYR activity in vitro and in vivo.CHMC-DOPA is constructed by incorporating dopamine(DOPA) moiety into a fluorescent chloro-hydroxyl-merocyanine(CHMC)scaffold.Upon exposure to TYR,the dopamine unit in CHMC-DOPA is oxidized to a dopaquinone derivative,and an intramolecular photo-induced electron transfer(PET) process between CHMC fluorophore and o-dopaquinone will take place,the fluorescence of CHMC-DOPA is quenched rapidly.Therefore,the evaluation of TYR activity is established in terms of the relationship between fluorescence quenching efficiency and TYR activity.In our experiments,CHMC-DOPA shows various advantages,such as fast response(8 min),low concentration of TYR activation(0.5 U/mL),good water-solubility,as well as the lowest detection limit(0.003 U/mL) compared with previously reported works.Furthermore,CHMCDO PA also exhibits excellent cell membrane permeability and low cytotoxicity,which is successfully used to monitor endogenous TYR activity in living cancer cells and zebrafish models.CHMC-DOPA performs well,and we anticipate that this newly designed novel platform will provide an alternative for high effective monitoring TYR activity in biosystems.
基金Science and Technology Program of Guangzhou,China(201510010218)National Key Project for Basic Research(973 project)(2015CB452802)+2 种基金National Natural Science Foundation of China(41675019,41475014,41475061,41675021 and 41475102)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA11010403)Natural Science Foundation of Guangdong Province of China(2016A030310009)
文摘This paper investigates processing of fast-response data and corrections of turbulent fluxes obtained by using eddy covariance method based on data collected at an offshore observation tower during three Cold-intrusion(CI)events in the South China Sea in 2010. This study presents the data processing procedure in detail and compares frictional velocities(u*), sensible heat fluxes(H) and latent heat fluxes(LE) yielded by using different averaging periods and different coordinate rotation methods; evaluates the sonic temperature correction for sensible heat flux and the Webb correction for latent heat flux as a function of 10 m wind speed(u10) during the CIs. The results show(1) that the different averaging periods of 30 min and 10 min cause biases of u*(H, LE) within 5%(15%, 62%). The values of u*(H,LE) averaged from 30 mins are mostly larger than those averaged from 10 mins. We suggest that the averaging period of 10 min is not sufficiently long to capture all scale eddies and recommend 30 min averaging period in calculating turbulent fluxes using eddy covariance method during CIs;(2) that the values of u*(H, LE) obtained from double rotation(DR2) and those obtained from planar fit rotation(PF) have good agreements and correlation coefficients between them are larger than 0.99. Because PF method requires unchanged environment and it is easier to apply DR2 method, we suggest DR2 coordinate rotation method in processing fast-response data; and(3) that the median values of frictional velocity(sensible heat flux and latent heat flux) binned according to 2 m s^(-1) intervals of u_(10) increase(decrease,increase) by less than 9%(4%, 10%) by Coriolis corrections(sonic temperature corrections, Webb corrections), which decreases(decreases, increases) with increasing u10 when u10 are 5-17 m s^(-1).
